When a plate material is punched using a punch press, burrs are always produced on the back surface of a punched portion of the plate material owing to a die clearance. To remove the burrs produced on the back surface of the plate material, the conventional art requires manual sanding of the plate material during a post-process or execution of a deburring step using a deburring machine. The need for the deburring step is a factor delaying the delivery of machined products and increasing costs.
The techniques described below have been proposed which carry out deburring using a punch press instead of the deburring executed during the post-process. One of the techniques involves providing a polishing member such as a buff sheet on a bottom surface of a punch tool or on a top surface of a die tool and rotating the tools with a punch hole portion of a plate material sandwiched between these tools to remove the burrs from the plate material (The Japanese Patent No. 3469929). Another technique involves providing a ball on the bottom surface of the punch tool or on the top surface of the die tool so that the ball can roll freely and sandwiching the punch hole portion of the plate material between these tools under pressure to remove the burrs from the plate material (The Unexamined Japanese Utility Model Application Publication (Jikkai-Hei) No. 3-42320).
Although not applied to deburring of the plate material, another technique provides balls on the bottom surface of the punch tool or on the top surface of the die tool and sandwiches the plate material between these tools to roll the plate material (U.S. Pat. No. 6,131,430 (PCT National Publication No. 2003-527965)).
The method in the Japanese Patent No. 3469929 provides the polishing member such as a buff sheet on the bottom surface of the punch tool or on the top surface of the die tool and rotates the tools with the plate material sandwiched between these tools. However, this method is effective on a thin plate material but does not produce a deburring effect on a thicker plate material. Further, the method in the Unexamined Japanese Utility Model Application Publication (Jikkai-Hei) No. 3-42320 provides the ball on the bottom surface of the punch tool or on the top surface of the die tool so that the ball can roll freely and sandwiches the punch hole portion of the plate material between these tools under pressure. However, this method is effective on a round punch hole but cannot carry out deburring on a slot.